During the construction, maintenance and modification of commercial air transports, it is often necessary to move large unitized complexes such as galleys and lavatories, as well as seat sections, stow bins, and other components, onto or off of the airplane. These complexes are usually built by off-site vendors as complete units sized to fit through the door of the airplane, but only just barely. They are large and bulky, offering few convenient handholds for lifting and maneuvering, and they are often very heavy, on the order of 800 pounds. They must be moved onto the airplane over the airplane floor which is designed to be as lightweight as possible consistent with its load bearing requirements. Accordingly, virtually all airplane floors are made of honeycomb panels, usually two graphite/epoxy skins bonded to a Nomex or aluminum foil honeycomb core. These panels are very strong for their weight, but can be damaged easily by concentrated loads, such as a corner of a piece of equipment being dropped on the panel. The repair of such damage is very expensive and time consuming and could affect the delivery schedule of the airplane, so every possible precaution is taken to avoid such damage.
As a consequence of the size, weight and bulk of these unitized complexes, and the necessity to protect the airplane floor from excessive concentrated loads, the complexes are moved onto the airplane by hand, usually with a crew of 6-8 strong men. However, since there are few if any handholds on the complexes, suction cups are usually applied to whatever flat smooth surfaces are available to provide attachment points by which the crew can lift the complex and muscle it through the airplane door and onto a set of skid rails placed on the floor, along which it is dragged to adjacent its final position. The crew then lifts the complex off the skid rails and onto its hard points for attachment to the airplane.
Although this procedure has been used for many, many years, it is fraught with the possibilities of injury to the workers, damage to the airplane and the complexes themselves, and is very time consuming, labor intensive, and interrupts other important work in progress in the airplane at the same time that the complexes are being installed. Injury to the workers is perhaps the most serious. The awkward position of necessity assumed by the workers as they maneuver the heavy, bulky complex through the airplane door exposes them to significant risk of injury, especially back injury, and indeed the medical history of workers in this job supports that conclusion. Aside from the human cost, the financial cost of all such injuries to the airframe manufacturer, in terms of workman's compensation claims and retraining of replacement workers, is enormous and contributes a significant fraction to the cost of producing an airplane.
The suction cup method of attaching hand holds to the complexes, which is the only know practical method that does not involve drilling or other disfiguring alterations to the structure, itself occasionally causes damage by pulling the laminate off the sides of the complex. This becomes a cost to the airframer because the complex was delivered to them undamaged, and aside from the cost, interferes with the build schedule because the damage must be repaired in situ and sometimes must be repaired before the complex can be finally installed. Occasionally the complex is dropped or run into some other structure on the airplane, inevitably causing damage to the honeycomb floor or aircraft interior.
Thus, there has existed for many years a serious unfulfilled need for a method and apparatus for moving large complexes and other unitized structures and components into an airplane, during final assembly and outfitting, in a way that is simple, easy, fast and does not expose the workers to risks of injury or cause damage to the airplane or the complexes themselves.